Compared with LCD, OLED (organic light-emitting device) has the advantages of self-luminescence, quick reaction, wide viewing angle, high brightness, vividness of color, light and thin appearance, and the like, and is thus considered to be the next generation of display technology.
The OLED thin film deposition method mainly includes vacuum vapor deposition and solution-based process. The vacuum vapor deposition is suitable for organic small molecule, which has the advantage of uniformity of film and is a relatively mature technology, but the equipment investment is big, the material utilization rate is low, and the alignment accuracy of a mask of the product in a large size is low. The solution-based process, comprising rotary coating method, inkjet printing method, nozzle coating method and the like, is suitable for polymer materials and soluble small molecules, and is characterized in low equipment costs, mass production and product in a large size.
Among them, inkjet printing technology can effectively and precisely spray ink to a pixel region, thereby forming an organic film layer. But, the most difficult problem thereof is that it is difficult for an organic solution to form an organic film layer with uniform thickness in a pixel region.